How will this pivotal jurist look upon Obamacare?

When the Supreme Court inevitably hears a challenge to Obamacare’s constitutionality, the outcome will be far from a sure thing. And the most important question is what Anthony Kennedy thinks.

The primary issue boils down to what the Constitution’s Commerce Clause and Necessary and Proper Clause mean. The Constitution gives the government the right to “regulate commerce . . . among the several states,” as well as to do everything that’s “necessary and proper” to achieve that regulation. Through the early 20th century, the Supreme Court enforced strict limits on these abilities, but since then, those limits have all but disappeared. The turning point was 1942’s Wickard v. Filburn, in which the Court held that the government can regulate how much wheat a farmer grows — even the wheat he plans to use on the farm instead of selling — on the grounds that such activity has a “substantial economic effect” on interstate commerce. Most recently, in 2005’s Gonzales v. Raich, the court held that the federal government could forbid California residents to grow and consume their own medical marijuana, which was legal under state law, on the grounds that some of the marijuana created this way might enter the illegal interstate market.

In the Obamacare case, the question is whether the Commerce Clause allows Congress to force people to buy insurance — that is, to regulate inactivity, or a person’s failure to engage in commerce. “It’s extremely powerful rhetorically to say that Congress has never done this before,” notes Nicholas Quinn Rosenkranz, an associate professor of law at Georgetown who clerked for Justice Kennedy, when asked what he thinks the justices will make of the distinction. “Nobody has been able to drum up an example.”

In theory, the Court could rule any of three ways. One, it could uphold the individual mandate. Two, it could strike the mandate down on the grounds that it goes beyond even the Court’s broad interpretation of the Commerce Clause. And three, it could interpret the Commerce Clause according to its original meaning, striking down Obamacare and paving the way for an avalanche of lawsuits against other government programs.

The first option is the best bet, the second is a distinct possibility, and the third is all but impossible. Here’s why.

The four liberal justices are almost certain to support the individual mandate, meaning that they need only one more vote for a majority. On the conservative side, they probably won’t find a friend in Clarence Thomas, who has tried repeatedly to return the Court to its old understanding of the Commerce Clause.

However, the two newest conservatives, John Roberts and Samuel Alito, have not left a consistent paper trail on the issue, and so their votes are hard to predict. In their confirmation testimony, both recognized that the Supreme Court has abandoned the original meaning of the Commerce Clause, but neither said what should be done about it. And Antonin Scalia sided with the majority in Raich (the marijuana case), which makes a pro-Obamacare vote a definite possibility for him.

Even assuming none of the conservatives sides with the Obama administration, there’s the question of Anthony Kennedy, the Court’s swing vote. His existing jurisprudence makes him a toss-up.

The Supreme Court has decided three major Commerce Clause cases since Kennedy joined in 1988: U.S. v. Lopez, U.S. v. Morrison, and Raich.

Lopez, decided in1995, was the first case since Wickard to limit the government’s power under the Commerce Clause. The court’s majority opinion, in which Kennedy joined, invalidated a federal law against bringing a firearm within 1,000 feet of a school. The government had argued that gun violence in schools harms the economy, discourages interstate travel, and inhibits learning (which in turn affects students’ ability to participate in commerce); in the view of the majority, these arguments were insufficient to tie the government’s actions to the interstate-commerce power.

Kennedy wrote a concurring opinion, which today is the most detailed record of his views on the Commerce Clause. He wrote that in light of the expanded view of the clause the Court had taken since Wickard, the majority opinion in which he’d joined “gives me some pause.” He made it absolutely clear that he has no intention of rolling the clause all the way back to its original meaning: “The Court as an institution and the legal system as a whole have an immense stake in the stability of our Commerce Clause jurisprudence as it has evolved to this point.” He went on to stress the importance of federalism, and argued that the Commerce Clause is not a license for the federal government to interfere in the traditional state concern of criminal justice. “Absent a stronger connection or identification with commercial concerns that are central to the Commerce Clause, that interference contradicts the federal balance the Framers designed and that this Court is obliged to enforce,” he concluded.

“I read [the Lopez concurrence] as Justice Kennedy trying to send two sets of signals,” says Michael C. Dorf, a professor at Cornell Law School and a former Kennedy clerk. “He wants to join the late chief justice [William Rehnquist] in saying there’s a limit to what Congress can do, but he also wants to reassure Congress and the interested public that he has no interest in substantially rolling back federal powers. He’s just affirming that there’s a line somewhere out there, and that Congress had crossed it in this case.”

Kennedy came to a similar conclusion in 2000’s U.S. v. Morrison. At issue was a provision of the Violence Against Women Act that allowed victims of sexual violence to file suit in federal court, even in cases where state law-enforcement agencies had not filed criminal charges. (Sexual violence, the government’s argument went, affected women’s ability to participate in commerce.) Kennedy joined in Rehnquist’s majority opinion, which invalidated the provision.

In Raich, however, Kennedy joined the liberal justices (plus Scalia) in John Paul Stevens’s majority opinion (which, again, held that the federal government can regulate marijuana that’s grown for private consumption).

Where does that put Kennedy on the Obamacare case? It’s hard to say; he seems cautious more than anything, and neither option here — striking down a presidential administration’s flagship accomplishment, or giving Congress the right to force people to buy the products of private businesses — fits that mold. “In a way, I see him as a small-C, Burkean conservative,” Dorf says. “Which leads me to think, although without overwhelming evidence, that whoever is able to frame this case as resistant to radical change will win it.”

It’s also worth bearing in mind what Dorf calls the “wild card” of the case: the argument that the individual mandate is a tax, and that therefore the government can implement it under its taxing powers rather than the Commerce Clause. This is a difficult argument for the Obama administration to make; during the Obamacare debate, when conservatives claimed the individual mandate violated the president’s pledge not to raise taxes for anyone making less than $200,000, Obama insisted it wasn’t a tax. However, Dorf notes that Kennedy has expressed dislike for a “jurisprudence of labels” — that is, court decisions that hinge on what something has been called, rather than what it is. It’s anybody’s guess what Kennedy (and the other judges, for that matter) will make of the argument that the ability to tax entails the ability to force people to purchase whatever the government wants them to, because there’s not much precedent for it.

With Kennedy as a coin flip, added to the possibility that any or all of Justices Scalia, Roberts, and Alito might side with the Court’s liberals, the most likely outcome is for Obamacare to be upheld. Thanks to more than a half century of rulings that treat the Commerce Clause as a license for the federal government to pass any law it wants, it will be difficult for the individual mandate’s opponents to convince the court that forcing people to buy insurance is a bridge too far.